Xcode Console "po" error: expression failed to parse

Question

My Xcode cannot po anything suddenly, such as:

po param

error: expression failed to parse:
error: Couldn't realize type of self.

Everytime I use "po" to print something in console, it will show the errors above. It happens one month ago.

user_2347811 · Answer

I know this does not fix the problem, but meanwhile you can use v param to achieve the expected result.

user_17296089 · Answer

well, you could click right button and choose "print..." at console.